One of the controversies in infectious diseases surrounds Lyme Disease. There is a large group of patients who, once adequately treated for the infection, continue to experience symptoms such as chronic pains, malaise, and related complaints.

Although patients--and some clinicians--attribute this to ongoing replication of Borrelia burgdorferi, there is no evidence that a chronic form of infection amenable to antimicrobial therapy exists. A recent paper has shown that some Borrelia antigens may persist in a mouse model, but that does not mean long term antimicrobial therapy is warranted or beneficial in humans. The IDSA guidelines, which unfortunately continue to spark controversy, reflect this position.

Many infectious disease physicians believe that post-Lyme symptoms are the result of the specific immune constitution of individuals and, as such, prolonged antimicrobial therapy offers no benefit as clinical trials have shown.

A recent study, published in Clinical Infectious Diseases, attempted to assess if there are immune differences in those that experience chronic Lyme symptoms. One of the fascinating results of this study was that, even prior to treatment, those that develop chronic Lyme symptoms have an altered polarity of their immune system when compared to those who suffer no chronic symptoms. Specifically, elevations of IL-23, a molecule which promotes the proliferation of Th 17 T cells, a specific class of immune cell linked to the development of autoimmune phenomena, were found to be associated with the development of chronic Lyme symptoms. One caveat: the study was conducted in Europe where B.afzelii is the culprit bacteria, which may limit its generalizability to the US setting.

The importance of this study is that it will, hopefully, dissuade those who demand chronic antimicrobial therapy from such requests while, at the same time, point the way towards fruitful areas of research that may yield effective treatment.